AP is neither underrated or overrated, he's #1 plain and simple. He doesn't garner the attention of Kaepernick or Wilson or RG3, so he fits the bill. Players love and respect him and he's a great dude. He's been injured how many times? And rushed for 2000 yards. He's the prototypical player of htis generation.
And he does the best rendition of Michael Jordan in the NFL. Doesn't need WR to catch the passes. Doesn't get yardage after catch credit like all QBs do. Make his own defender miss. Catch passes in the backfield. Opens opportunity for WRs to get opportunity. Just a few things Adrian Peterson does that those other #1 don't and can't do.
All QBs(excluding Cam) do is throw a football. AP is the best player in the league. No contest.